Calculations on the size effects of Raman intensities of silicon quantum dots

Abstract

Raman intensities of Si quantum dots ͑QD's͒ with up to 11489 atoms ͑about 7.6 nm in diameter͒ for different scattering configurations are calculated. First, phonon modes in these QD's, including all vibration frequencies and vibration amplitudes, are calculated directly from the lattice-dynamic matrix by using a microscopic valence force field model combined with the group theory. Then the Raman intensities of these quantum dots are calculated by using a bond-polarizability approximation. The size effects of the Raman intensity in these QD's are discussed in detail based on these calculations. The calculations are compared with the available experimental observations. We are expecting that our calculations can further stimulate more experimental measurements.

Modified phonon confinement model for size dependent Raman shift and linewidth of silicon nanocrystals

“…In Fig. 4, BP model [8] Cheng theory [4] Present theory Xia data [3] RWL model [8] Richter data [10] Pennisi data [9] Paillard data [8] Li data [6] Faraci data [12] Sirekno data [7] Peak Shift (cm…”

“…In recent years the finite size effects on the Raman spectrum of a nanocrystal silicon have attracted considerable interest [1,2] due to the role of Si in the current semiconductor industry and potential technological applications [3][4][5] resulting from the optical properties of Si quantum dots. However, most of the efforts are dedicated to interpret the experimental Raman spectra particularly in terms of confinement effect, which in 0D systems are difficult to evidence experimentally by Raman shift in contrast to 2D and 1D nanostructures.…”

“…The models [4][5][6][7][8][13][14] including the many version of phonon confinement model [9][10][11][12] of Si [7,17], the size distribution has its importance for the smaller particle as has been pointed by Diẻguez et al [18] in the case SnO 2 nanoparticles. The importance of phonon dispersion curves for the asymmetric broadening and shifting of Raman peak is already pointed out for the zinc and thorium oxide by Arora et al [16].…”

“…To obtain a good interpretation of the experimental data many other models such as the microscopic force model [4], the bond polarizable model [13][14] and the spatial correlation model [15] have been reported. But these models do not satisfactorily describe the phonon confinement and are fail in explaining the experimental data particularly the shift and linewidth of the peak simultaneously.…”

The pronounced role of impurity phases in the optical properties of Mn catalyzed ZnS nanostructures

“…The interface phonon modes originate at the interface formed by different dielectric function surfaces and it travels along the interface. 29 For the interpretation of Raman spectra, several models have been employed extensively, which included microscopic force model, 30 bond polarization model, 31,32 and spatial correlation model. 33 Fauchet and Campbell generalized the spatial correlation model, originally proposed by Ritcher for the interpretation of Raman lineshape observed from the microstructures.…”